1990 GMC C3500 Spits and Spudders

I have a 90 gmc dump with a 454 motor. One day I was Driveing and it started to spit and spudder and back fire. I used my scan tool and got the codes. I had to replace the TPS and MAP Sencors. I did that and it cleared the codes. But still acts up. I even changed the fuel pump and fuel filter and the fuel pressure regulater. Notthing seems to help I hope u can help me out

Thanks justin